EFFORTS to rescue 12 boys and their football coach trapped in a cave in Thailand are being hampered by heavy rainfall.

Muddy water rising to the ceiling of one of the chambers has prevented divers from progressing farther into the cave to where they think the young footballers and their coach, who went missing on Saturday, may be sheltering.

There has been no contact with the group since they entered the Tham Luang Nang Non cave in Chiang Rai province.

At the entrance to the cave, officials were bringing in large water hoses and more water pumps. Navy divers who have been working their way through the complex said that water levels were rising in some places at a rate of 15 centimetres per hour early on Wednesday.

Chiang Rai governor Narongsak Osatanakorn said: “We tried to pump the water (out of the chamber) but the water keeps rising. That means the water that comes in with the rain is still much more than what we can pump out. So we need to pump the water faster.”

He said teams continued to look for another way in to the blocked parts of the cave by searching for any shafts that might be accessible on the surface of the mountain, under which the cave sits.

Despite setbacks, officials remained publicly optimistic about the prospects for a successful rescue.